The advantages of image guided all field synchronous radiation therapy is described in U.S. Provisional Patent Application No. 60/790,192 filed on Apr. 6, 2006, its regular Utility patent application Ser. No. 11/784,398 Filed on Apr. 5, 2007, its continuation application Ser. No. 11/974,876 filed on Oct. 15, 2007 “Multiple Medical Accelerators and kV-CT Incorporated Radiation Therapy Device and Semi-Automated Custom Reshapeable Blocks for All Field Synchronous Image Guided 3-D Conformal-Intensity Modulated Radiation Therapy”, Provisional Patent Application 60/872,117 of Nov. 30, 2006, its regular Utility patent application Ser. No. 11/998,063, filed on Nov. 27, 2007 “Lethal and Sublethal Damage Repair Inhibiting Image Guided Simultaneous All Field Divergent and Pencil Beam Photon and Electron Radiation Therapy and Radiosurgery”, Provisional Patent Application 60/872,115 of Nov. 30, 2006, its regular utility patent application Ser. No. 11/998,064 filed on Nov. 27, 2007, “Lethal and Sublethal Damage Repair Inhibiting Image Guided Split Dose, Few Seconds Interval Divergent and Pencil Photon and Electron Radiation Beams Radiation Therapy and Radiosurgery”, Provisional Patent Application 60/927,622 filed on May 3, 2007, “Single Session Interactive Image Guided Simulation, Field Shaping, Treatment Planning and Ultra Short Duration Super-High Biological Dose Rate All Field Simultaneous or Sequential Radiation Therapy and Radiosurgery” and their related Disclosure Document 561105 filed on Sep. 14, 2004.
The methods of kV CT and MV-CT are described in the above cross-referenced applications. They are modified and adapted in this invention's online dynamic interactive viewing of the surface and internal anatomy as 3-D and 4-D VR CT or 3-D and 4-D VR MRI images and treatment planning. When the Medical Accelerator System is combined with CT imaging only, the CT imaging is used for interactive single session combined simulation, block making and treatment planning and radiation therapy. When the Medical Accelerator System is equipped with both CT and MRI imaging capabilities, CT and MRI imaging is used for interactive single session combined simulation, block making, treatment planning and radiation therapy. CT-MRI fused images are used for the treatment planning. It overcomes the difficulties associated with MRI's non-correlating pixel intensities between bone-air interface as with MRI of the sinuses. It also eliminates the need to introduce an endorectal probe for MRI of the prostate. The fused CT-MRI image provides sufficient imaging details of the prostate for the treatment planning.
The MRI also facilitates to do the functional imaging by magnetic resonance spectroscopic imaging (MRSI). The CT combined with MRI and functional imaging the MRSI are also used for online dynamic interactive views of the surface and internal anatomy of the treating tumor volume. The tumor volume is visualized as 3-D and 4-D VR images on a stereoscopic screen and as 2-D images on a 2-D monitor. It has greater significance in radiation therapy of cancer. It helps to improve precise simulation, block making and treatment planning and to improve the quality of radiation therapy.
The Medical Accelerator systems described in Provisional Patent Application 60/872,117 of Nov. 30, 2006, Lethal and Sublethal Damage Repair Inhibiting Image Guided Simultaneous All Field Divergent and Pencil Beam Photon and Electron Radiation Therapy and Radiosurgery facilitates actual beam on time to complete radiation therapy to all the setup fields in about 5 seconds and radiosurgery in about 30 seconds. Since a patient can hold breathing for more than 40 seconds, the breathing associated organ movement is not a hindrance to deliver accurate radiation therapy with the Medical Accelerator System describe in the above Provisional Patent Application 60/872,117. It simplifies the single session radiation therapy and radiosurgery to a patient with more precision and with limited patient fixation to the treatment table. It improves the patient's comfort significantly.
The single session simulation, block making, treatment planning and radiation therapy eliminates the protracted six to seven week long multiple session radiation therapy. In multiple session radiation therapy, reproduction of the same treatment setup for the daily treatment is an almost impossible task. Hence the single session treatment as described here further enhances the quality of the treatment.
Single Session All Field Simultaneous Radiation Therapy's Effective Dose Rate Equivalence to I-125 Implant, Conventional Radiation Therapy and IMRT and the Effective Dose Rate of Radiosurgery with Gamma Knife by Multiple Isocenters
Total Dose and Dose Rate in I-125 Brachytherapy
Brachytherapy with radioactive seeds has similarities to All Field Simultaneous Radiation Therapy (AFSRT) with multiple accelerators. In both radiation is rendered from multiple sources of radiation. Brachytherapy is a long duration radiation therapy with many radioactive seeds implanted into a single field made of multiple smaller fields in which the radiation from the implanted multiple radioactive seed's fuse together to give the implant volume radiation and the dose rate. If 20,736 cGy total dose is given by I-125 implant, its initial dose rate is 10 cGy/h. It is derived from the formula: Total dose=initial dose rate×Tave. Tave is the mean life. The Tave of I-125 is 1.44×T1/2=1.44×60 days=2073.6 hr; the T1/2 for I-125=60 days. Hence the initial dose rate is 20,736/2,076.6=10 cGy/h. It is 0.1667 cGy/min or 0.0028 cGy/sec.
Effective Dose Rate in Conventional Radiation Therapy and IMRT when Machine Dose Rate is 400 cGy/min
In conventional IMRT and radiosurgery, with radiation from multiple external beams, each fields of a multiple treatment setup is treated with a radiation beam. Each of those fields is treated as one field at a time. In this instance, the daily radiation therapy is rendered as sub-fractionated radiation. The cumulative dose of about 8,000 cGy of the conventional IMRT is rendered as fractionated daily dose of about 200 cGy and as five treatments in a week and no treatments on weekends. It lasts eight weeks of treatment or an overall treatment time of 56 days or 56×24 hours, that is in 1,344 hours. Since 8,000 cGy is given in an overall elapsed time of 1,344 hours, its overall dose rate is 5.9524 cGy/h or say, 6 cGy/h. It is 0.0992 cGy/min or say, 0.1 cGy/min which is 0.0017 cGy/sec.
Effective Dose Rate in AFSRT Versus Conventional IMRT when Machine Dose Rate is 400 cGy/min
In AFSRT radiation to all the fields is rendered simultaneously with multiple external beams, each beams coming from each of the multiple accelerators containing radiation therapy machine. All the beams from a multiple field setup treatment converge together at the tumor site in a patient. At 400 cGy/min machine dose rate, it renders 200-cGy to the tumor in 5 seconds. Hence, its dose rate is 40 cGy per second. Compared to the above conventional IMRT's 0.0017 cGy/sec, this 40-cGy/sec-dose rate of AFSRT is 40/0.0017, which is 23,529. It is 23,529 times higher than the conventional IMRT's dose rate of 0.0017 cGy.
Effective Dose Rate in AFSRT Versus Conventional Radiosurgery with Multiple Isocenters as in Radiosurgery with Gamma Knife
In AFSRT, 200 cGy could be delivered to a tumor in 5 seconds. Hence its dose rate is 40 cGy/sec.
The time taken to deliver 1,000 cGy to a tumor by radiosurgery with Gamma Knife and by multiple isocenters is about 3 hours (9). It is 333.33 cGy/h, 5.55 cGy/min and 0.0926 cGy/sec
Since in the above example conventional radiosurgery rendered in 3 hours its dose rate is 0.0926 cGy/sec. The comparative dose rate for AFSRT-radiosurgery is 0/0.0926=432 times higher.